Australian University Leading The charge for Panel Powered Car

QUT leading the charge for panel-powered car

QUT (Queensland University of Technology)

06 November 2014

A car powered by its own body panels could soon be driving on our roads after a breakthrough in nanotechnology research by a QUT team.

[caption id="attachment_217" align="aligncenter" width="660"] QUT's Professor Nunzio Motta with one of the university's powerful nanotechnology microscopes.[/caption]

Researchers have developed lightweight "supercapacitors" that can be combined with regular batteries to dramatically boost the power of an electric car.

The discovery was made by Postdoctoral Research Fellow Dr Jinzhang Liu, Professor Nunzio Motta and PhD researcher Marco Notarianni, from QUT's Science and Engineering Faculty - Institute for Future Environments, and PhD researcher Francesca Mirri and Professor Matteo Pasquali, from Rice University in Houston, in the United States.

The supercapacitors - a "sandwich" of electrolyte between two all-carbon electrodes - were made into a thin and extremely strong film with a high power density.

The film could be embedded in a car's body panels, roof, doors, bonnet and floor - storing enough energy to turbocharge an electric car's battery in just a few minutes.

The findings, published in the Journal of Power Sources and the Nanotechnologyjournal, mean a car partly powered by its own body panels could be a reality within five years, Mr Notarianni said.

"Vehicles need an extra energy spurt for acceleration, and this is where supercapacitors come in. They hold a limited amount of charge, but they are able to deliver it very quickly, making them the perfect complement to mass-storage batteries," he said.

"Supercapacitors offer a high power output in a short time, meaning a faster acceleration rate of the car and a charging time of just a few minutes, compared to several hours for a standard electric car battery."

Dr Liu said currently the "energy density" of a supercapacitor is lower than a standard lithium ion (Li-Ion) battery, but its "high power density", or ability to release power in a short time, is "far beyond" a conventional battery.

"Supercapacitors are presently combined with standard Li-Ion batteries to power electric cars, with a substantial weight reduction and increase in performance," he said.

"In the future, it is hoped the supercapacitor will be developed to store more energy than a Li-Ion battery while retaining the ability to release its energy up to 10 times faster - meaning the car could be entirely powered by the supercapacitors in its body panels.

"After one full charge this car should be able to run up to 500km - similar to a petrol-powered car and more than double the current limit of an electric car."

Dr Liu said the technology would also potentially be used for rapid charges of other battery-powered devices.

"For example, by putting the film on the back of a smart phone to charge it extremely quickly," he said.

The discovery may be a game-changer for the automotive industry, with significant impacts on financial, as well as environmental, factors.

"We are using cheap carbon materials to make supercapacitors and the price of industry scale production will be low," Professor Motta said.

"The price of Li-Ion batteries cannot decrease a lot because the price of Lithium remains high. This technique does not rely on metals and other toxic materials either, so it is environmentally friendly if it needs to be disposed of."

The researchers are part of QUT's Battery Interest Group, a cross-faculty group that aims to engage industry with battery-related research.

News Release Source : QUT leading the charge for panel-powered car

DNA Origami to Turn One-Dimensional Nano Materials into Two Dimensions

Nano-platform ready: Scientists Use DNA Origami to Create 2-D Structures

Scientists at New York University and the University of Melbourne have developed a method using DNA origami to turn one-dimensional nano materials into two dimensions. Their breakthrough, published in the latest issue of the journal Nature Nanotechnology, offers the potential to enhance fiber optics and electronic devices by reducing their size and increasing their speed.

[caption id="attachment_212" align="alignleft" width="354"] Scientists Use DNA Origami to Create 2-D Structures[/caption]

"We can now take linear nano-materials and direct how they are organized in two dimensions, using a DNA origami platform to create any number of shapes," explains NYU Chemistry Professor Nadrian Seeman, the paper's senior author, who founded and developed the field of DNA nanotechnology, now pursued by laboratories around the globe, three decades ago.

Seeman's collaborator, Sally Gras, an associate professor at the University of Melbourne, says, "We brought together two of life's building blocks, DNA and protein, in an exciting new way. We are growing protein fibers within a DNA origami structure."

DNA origami employs approximately two hundred short DNA strands to direct longer strands in forming specific shapes. In their work, the scientists sought to create, and then manipulate the shape of, amyloid fibrils—rods of aggregated proteins, or peptides, that match the strength of spider's silk.

To do so, they engineered a collection of 20 DNA double helices to form a nanotube big enough (15 to 20 nanometers—just over one-billionth of a meter—in diameter) to house the fibrils.

The platform builds the fibrils by combining the properties of the nanotube with a synthetic peptide fragment that is placed inside the cylinder. The resulting fibril-filled nanotubes can then be organized into two-dimensional structures through a series of DNA-DNA hybridization interactions.

"Fibrils are remarkably strong and, as such, are a good barometer for this method's ability to form two-dimensional structures," observes Seeman. "If we can manipulate the orientations of fibrils, we can do the same with other linear materials in the future."

Seeman points to the promise of creating two-dimensional shapes on the nanoscale.

"If we can make smaller and stronger materials in electronics and photonics, we have the potential to improve consumer products," Seeman says. "For instance, when components are smaller, it means the signals they transmit don't need to go as far, which increases their operating speed. That's why small is so exciting—you can make better structures on the tiniest chemical scales."

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The research was supported by grants from the National Institute of General Medical Sciences, part of the National Institutes of Health (GM-29554), the National Science Foundation (CMMI-1120890, CCF-1117210), the Army Research Office (MURI W911NF-11-1-0024), the Office of Naval Research (N000141110729, N000140911118), an Australian Nanotechnology Network Overseas Travel Fellowship, a Melbourne Abroad Travelling Scholarship, the Bio21 Institute and Particulate Fluids Processing Centre. The work was carried out, in part, at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences.

Image Credit : kentoh/iStock

News Release Source :   Nano-platform ready: Scientists Use DNA Origami to Create 2-D Structures

Nanochannel Flow by Quantum Mechanics

Nanochannel Flow by Quantum Mechanics

Explanations of the surprisingly high flow observed in nanochannels by fluid slip at the channel walls are superseded by QED induced ionization of fluid molecules to produce frictionless flow as atoms undergo Coulomb repulsion.

PRLog (Press Release) - Jan. 23, 2014 - YOUNGWOOD, Pa. -- ,

Introduction
Liquid flow through nanochannels of carbon nanotubes and thin films has been observed [1-3] to be 2-5 orders of magnitude higher than predicted by assuming a no-slip condition at the channel wall as in the Hagen-Poiseuille equation of continuum mechanics. To explain this disparity, the fluid is generally thought to slip at the channel wall, but this is questionable because the calculated slip-lengths necessary to explain the flow enhancement exceed the typical slip on non-wetting surfaces by 2 to 3 orders of magnitude. Hence, fluid slip at the channel wall is an unlikely explanation for the observed flow enhancement in nanochannels.

[caption id="attachment_207" align="aligncenter" width="507"] Nanochannel Flow by Quantum Mechanics[/caption]

Instead, flow enhancement is more likely caused by the size effect of QM that causes the viscosity of the fluid to vanish in nanochannels that otherwise does not occur at the macroscale. QM stands for quantum mechanics. Since vanishing viscosity allows the Hagen-Poiseuille equation to remain valid,  MD was performed to show the viscosity does indeed vanish in nanochannels. MD stands for molecular dynamics.

Background
MD is commonly used [4,5] to explain enhanced nanochannel flow. However, the MD simulations are not valid because QM precludes the atom from having the heat capacity to conserve fluid friction by an increase in temperature. Instead, QED induces atoms in fluid molecules under the TIR confinement of the nanochannel to conserve frictional heat by the creation of EM radiation. QED stands for quantum electrodynamics, TIR for total internal reflection, and EM for electromagnetic. Standard MD computer programs assume the atom has heat capacity, and therefore to obtain valid MD solutions require modification to simulate the QM effect of a vanishing heat capacity on viscosity. See http://www.prlog.org/11774079-validity-of-molecular-dynam...

Application to Nanochannels
In nanochannels, the QM effect during fluid flow is illustrated in the thumbnail. The EM radiation from a laser heats the molecules in the nanochannel while QED conserves the heat by creating EM radiation that ionizes the molecules. However, lasers are not required. Indeed, the fluid molecules flowing through the nanochannel produce viscous frictional heat that is induced by QED to create ionizing EM radiation at the TIR confinement wavelength λ of the nanochannel, Here, λ = 2 nd, where n and d are the refractive index of the fluid and d the tube diameter or thin film thickness.  For d < 100 nm,the EM radiation has wavelengths λ in the UV and beyond, i.e., λ < 300 nm. Therefore, QED induced EM radiation in nanochannels has sufficient Planck energy to ionize most fluid molecules having ionization potentials of ~ 10 eV corresponding to  λ < 125 nm or d < 45 nm for n = 1.5. What this means is the fluid in nanochannels is charged with Coulomb repulsion between atoms tending to avoid atom contact and reduce viscosity.

The reduction in viscosity may be understood by considering the L-J potential between fluid and wall atoms. L-J stands for Lennard-Jones. Here, L-J parameter σ is the repulsive atom core and ε the attractive potential. The Coulomb potential repulses charged atoms to counter the attractive ε potential, and therefore the viscosity is reduced. A similar QM effect occurs as nanocrystals under Joule heating flow through smaller nanopores by Coulomb repulsion of QED induced ionized atoms. Seehttp://www.prlog.org/12245294-qed-charging-of-metal-nanoc...

MD Simulation and Results
The MD simulates a 2D model comprising 100 atoms in a BCC configuration of liquid argon under a constant shear stress. The BCC configuration has atomic spacing of 5.61 Å. The L-J potential is chosen to have σ = 3.45 Å and ε / k = 120, where k is Boltzmann’s constant. The MD computation box is 61.3 Å square. Time steps were < 2 fs.

The MD loading imposed a velocity gradient 1.6 x10¹⁰ / s normal to the flow direction having velocity of 100 m/s over the height of the  MD box.  After 150000 iterations, the L-J viscosity converged to ~ 80 micro-Pa-s. Experimentally, the viscosity of liquid argon depends on temperature and varies from 54 to 200 micro-Pa-s. But agreement between the MD simulation and experiment is not necessary as the purpose was to show the effect of Coulomb repulsion of charged atoms on viscosity.

Instead of performing MD for repulsive Coulomb forces between atoms including the attractive L-J potential ε, the Coulomb repulsion was first simulated by neglecting Coulomb repulsion and simply reducing the attractive L-J potential ε by a factor of 100. However, the MD solution diverged in < 20000 iterations suggesting the viscosity did indeed vanish. Because of this, MD solutions including Coulomb repulsion without reducing the attractive potential were not necessary to show frictionless flow in nanochannels. See Nanochannel Flow at http://www.nanoqed.org , 2014.

Conclusions
1. Slip-lengths [1,2] finding origin in classical physics cannot explain high flow observed in nanochannels. However, arguments [3] that limitless flow observed in nanochannels is precluded by frictional losses at the end of the channel are indeed valid. Ionization of atoms and recombination of charges is very rapid and continually occurring within the nanochannel, but as the atoms leave the channel there is no TIR confinement allowing the atom to regain its classical behavior causing frictional losses to indeed occur.

2. Claims [4] high nanochannel flow can be fully explained in the context of continuum fluid mechanics thereby justifying the lower flow enhancements predicted by MD are not valid. Nanochannel flow does not follow continuum mechanics, but rather QM. In fact, QED induced frictionless flow in nanochannels are likely to produce reported flow enhancements above Hagen-Poiseuille theory.

3. Under TIR confinement in nanochannels, QM denies the atom the heat capacity to conserve frictional viscous heating by an increase in temperature. Temperature changes simply do not occur in nanochannels. MD solutions [5] showing otherwise are invalid by QM. Instead, the viscous heating is conserved by QED inducing creation of EM radiation that ionizes the atoms to produce Coulomb repulsion that negates the fluid viscosity in the Hagen-Poiseuille equation to explain the reported flows.

References
[1] M. Majunder, et al., “Nanoscale hydrodynamics: Enhanced flow in carbon nanotubes,” Nature 438, 44, 2005.
[2] F. Du, “Membranes of Vertically Aligned Superlong Carbon Nanotubes,” Langmuir, 27, 8437, 2011.
[3] T. Sisan and S. Lichter, “The end of nanochannels,” Microfluid-Nanofluid, 11, 787, 2011.
[4] J. Thomas and A. McGaughey, “Reassessing Fast Water Transport Through Carbon Nanotubes. Nano Lett., 8, 2788, 2008.
[5] Z. Li, “Surface effects on friction-induced fluid heating in nanochannel flows,” Phys. Rev. E, 79, 026312, 2009.

Photo:
http://www.prlog.org/12271497/1

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News Release Source :  Nanochannel Flow by Quantum Mechanics

Gold Nanomesh Electrodes : New Flexible Transparent Conductor

UH researchers create new flexible, transparent conductor

Discovery brings bendable cell phone, foldable flat-screen TV closer to reality

University of Houston researchers have developed a new stretchable and transparent electrical conductor, bringing the potential for a fully foldable cell phone or a flat-screen television that can be folded and carried under your arm closer to reality.

[caption id="attachment_202" align="aligncenter" width="500"] Gold Nanomesh Electrodes : New Flexible Transparent Conductor[/caption]

Zhifeng Ren, a physicist at the University of Houston and principal investigator at the Texas Center for Superconductivity, said there long has been research on portable electronics that could be rolled up or otherwise easily transported. But a material that is transparent and has both the necessary flexibility and conductivity has proved elusive – some materials have two of the components, but until now, finding one with all three has remained difficult.

The gold nanomesh electrodes produced by Ren and his research associates Chuan Fei Guo and Tianyi Sun at UH, along with two colleagues at Harvard University, provide good electrical conductivity as well as transparency and flexibility, the researchers report in a paper published online Tuesday in Nature Communications.

The material also has potential applications for biomedical devices, said Ren, lead author on the paper. The researchers reported that gold nanomesh electrodes, produced by the novel grain boundary lithography, increase resistance only slightly, even at a strain of 160 percent, or after 1,000 cycles at a strain of 50 percent. The nanomesh, a network of fully interconnected gold nanowires, has good electrical conductivity and transparency, and has "ultrahigh stretchability," according to the paper.

And unlike silver or copper, gold nanomesh does not easily oxidize, which Ren said causes a sharp drop in electrical conductivity in silver and copper nanowires. Guo said the group is the first to create a material that is more stretchable and conductive at similar transparency, as well as the first to use grain boundary lithography in the quest to do so. More importantly, he said, it is the first to offer a clear mechanism to produce ultrahigh stretchability.

The grain boundary lithography involved a bilayer lift-off metallization process, which included an indium oxide mask layer and a silicon oxide sacrificial layer and offers good control over the dimensions of the mesh structure.

"This is very useful to the field of foldable electronics," Guo said. "It is much more transportable." Sun noted that Korean electronics maker Samsung demonstrated a cellphone with a bendable screen in October; LG Electronics has introduced a curved cellphone that is available now in Asia.

But neither is truly foldable or stretchable, instead curving slightly to better fit against the user's face. "For that kind of device, we need something flexible, transparent," Sun said of a foldable phone. "If we want to further that technology, we need something else, and the something else could be the technology we are developing."

Ren noted that, although gold nanomesh is superior to other materials tested, even it broke and electrical resistance increased when it was stretched. But he said conductivity resumed when it was returned to the original dimensions.

That didn't prove true with silver, he said, presumably because of high oxidation. The work at the University of Houston was funded by the Department of Energy, while that at Harvard was funded by a National Science Foundation grant.

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About the University of Houston

The University of Houston is a Carnegie-designated Tier One public research university recognized by The Princeton Review as one of the nation's best colleges for undergraduate education. UH serves the globally competitive Houston and Gulf Coast Region by providing world-class faculty, experiential learning and strategic industry partnerships. Located in the nation's fourth-largest city, UH serves more than 39,500 students in the most ethnically and culturally diverse region in the country.

News Release Source :  UH researchers create new flexible, transparent conductor

Asymmetric Graphene Nanoribbons - New Devices That Control Heat Flow

Research could bring new devices that control heat flow

WEST LAFAYETTE, Ind. — Researchers are proposing a new technology that might control the flow of heat the way electronic devices control electrical current, an advance that could have applications in a diverse range of fields from electronics to textiles.

The concept uses tiny triangular structures to control "phonons," quantum-mechanical phenomena that describe how vibrations travel through a material's crystal structure.

[caption id="attachment_197" align="aligncenter" width="500"] Asymmetric Graphene Nanoribbons - New Devices That Control Heat Flow[/caption]

Findings in research using advanced simulations show the triangular or T-shaped structures - if small enough in width - are capable of "thermal rectification," or permitting a greater flow of heat in one direction than in the opposite direction, said Xiulin Ruan, an associate professor in Purdue University's School of Mechanical Engineering and Birck Nanotechnology Center.

Rectification has made possible transistors, diodes and memory circuits central to the semiconductor industry. The new devices are thermal rectifiers that might perform the same function, but with phonons instead of electrical current.

"In most systems, heat flow is equal in both directions, so there are no thermal devices like electrical diodes. However, if we are able to control heat flow like we control electricity using diodes then we can enable a lot of new and exciting thermal devices including thermal switches, thermal transistors, logic gates and memory," said Ruan, whose research group collaborated with a group led by Yong Chen, an associate professor in Purdue's Department of Physics and School of Electrical and Computer Engineering. "People are just starting to understand how it works, and it is quite far from being used in applications."

Findings are detailed in a research paper that has appeared online in the journal Nano Letters and will be published in an upcoming issue of the journal. The paper was authored by doctoral students Yan Wang, Ajit Vallabhaneni and Jiuning Hu and former doctoral student Bo Qiu; Chen; and Ruan.

The researchers used an advanced simulation method called molecular dynamics to demonstrate thermal rectification in structures called "asymmetric graphene nanoribbons." Molecular dynamics simulations can simulate the vibrations of atoms and predict the heat flow in a material.

Graphene, an extremely thin layer of carbon, is promising for applications in electronics and computers. The triangular structure must be tiny in width to make possible the "lateral confinement" of phonons needed for the effect. Findings also show thermal rectification is not limited to graphene but could be seen in other materials in structures such as pyramidal, trapezoidal or T-shaped designs.

Hu, Ruan, and Chen also published a paper four years ago in the journal Nano Letters, among the first to propose asymmetric graphene nanoribbons as a thermal rectifier in research using the molecular dynamics simulations. Although numerous studies have been devoted to this topic since then, until now researchers did not know the mechanism behind thermal rectification. The new findings show that this mechanism works by restricting vibrations as they travel through the small lateral direction of an asymmetrical structure.

"We demonstrate that other asymmetric materials, such as asymmetric nanowires, thin films, and quantum dots of a single material can also be high-performance thermal rectifiers, as long as you have lateral confinement," Ruan said. "This really broadens the potential of this rectification to a much wider spectrum of applications."

Thermal rectification is not seen in larger triangular-shape structures because they lack lateral confinement. In order for lateral confinement to be produced, the cross section of the structure must be much smaller than the "mean free path" of a phonon, or only a few to hundreds of nanometers depending on the material, Wang said.

"This is the average distance a phonon can travel before it collides with another phonon," he said. However, although the devices must be tiny, they could be linked in series to produce larger structures and better rectification performance. The concept could find uses in "thermal management" applications for computers and electronics, buildings and even clothing.

"For example, on a winter night you don't want a building to lose heat quickly to the outside, while during the day you want the building to be warmed up by the sun, so it would be good to have building materials that permit the flow of heat in one direction, but not the other," Ruan said.

A potential, although speculative, future application could be thermal transistors. Unlike conventional transistors, thermal transistors would not require the use of silicon, are based on phonons rather than electrons and might make use of the large amount of waste heat that is already generated in most practical electronics, said Chen.

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The research was funded by the U.S. Air Force Office of Scientific Research.

Writer: Emil Venere, 765-494-4709, venere@purdue.edu

Sources: Xiulin Ruan, 765-494-5721, ruan@purdue.edu
Yong P. Chen, 765-494-0947, yongchen@purdue.edu

IMAGE CAPTION:

Researchers are proposing a new technology that controls the flow of heat the way electronic devices control electrical current. Triangular graphene nanoribbons (a) are proposed as a new thermal rectifier, in which the heat flow in one direction is larger than that in the opposite direction. Thermal rectification (b) is not limited to graphene, but can also be seen in other "asymmetric nanostructure materials" including thin films, pyramidal quantum dots, nanocones and triangles. (Purdue University image)

A publication-quality graphic is available at http://www.purdue.edu/uns/images/2014/ruan-rectification.jpg

ABSTRACT

Phonon Lateral Confinement Enables Thermal Rectification in Asymmetric Single-Material Nanostructures
Yan Wang,†,‡ Ajit Vallabhaneni,†,‡ Jiuning Hu,‡,§ Bo Qiu,†,‡ Yong P. Chen,‡,§,∥ and Xiulin Ruan*,†,‡
† School of Mechanical Engineering, Purdue University
‡ Birck Nanotechnology Center, Purdue University
§ School of Electrical and Computer Engineering, Purdue University
∥Department of Physics, Purdue University

We show that thermal rectification (TR) in asymmetric graphene nanoribbons (GNRs) is originated from phonon confinement in the lateral dimension, which is a fundamentally new mechanism different from that in macroscopic heterojunctions. Our molecular dynamics simulations reveal that, though TR is significant in nanosized asymmetric GNRs, it diminishes at larger width. By solving the heat diffusion equation, we prove that TR is indeed absent in both the total heat transfer rate and local heat flux for bulk-size asymmetric single materials, regardless of the device geometry or the anisotropy of the thermal conductivity. For a deeper understanding of why lateral confinement is needed, we have performed phonon spectra analysis and shown that phonon lateral confinement can enable three possible mechanisms for TR: phonon spectra overlap, inseparable dependence of thermal conductivity on temperature and space, and phonon edge localization, which are essentially related to each other in a complicated manner. Under such guidance, we demonstrate that other asymmetric nanostructures, such as asymmetric nanowires, thin films, and quantum dots, of a single material are potentially high-performance thermal rectifiers.

Note to Journalists: An electronic copy of the research paper is available from Emil Venere, 765-494-4709, venere@purdue.edu

News Release Source :  Research could bring new devices that control heat flow